First Pacific Record of the Rare Scaleless Dragonfish Grammatostomias circularis (Teleostei: Stomiiformes: Stomiidae) from the Ogasawara Islands, Japan

Abstract

A single specimen of a scaleless dragonfish in the genus Grammatostomias Goode and Bean, 1896 (Teleostei: Stomiiformes: Stomiidae) was collected off the Ogasawara Islands, Japan at a depth between 40–780 m. The specimen conformed to G. circularis Morrow, 1959 in having the following characters: dorsal-fin rays 21; anal-fin rays 23; pectoral-fin rays 9; the first pectoral-fin ray not isolated; and entire luminous loop on lateral body surface very thin, almost circular and without zigzags. The likelihood of the distribution pattern of small areas of luminous tissue on the head being diagnostic for each species of Grammatostomias is briefly considered. Grammatostomias circularis has previously been recorded only from the Atlantic, the present specimen representing the first record of the species from the Pacific Ocean, and first record of a species of Grammatostomias from Japan.

Keywords

• bonin islands
• luminous loop
• luminous tissue
• melanostomiinae
• mesopelagic fish
• northwest pacific